ok,On my server,I think the problem might be the proxy issue(I use a ssh vpn to access facebook api). the log like this:
23:05:34.038893 WARNING: Couldn’t interpret error type url.Error, value Get https://graph.facebook.com/me?access_token=&fields=id%2Cname%2Cemail: x509: certificate is valid for www, , not graph.facebook.com – base.ErrorAsHTTPStatus() at error.go:63
23:05:34.038963 HTTP: #283: --> 500 Internal error: Get https://graph.facebook.com/me?access_token=&fields=id%2Cname%2Cemail: x509: certificate is valid for www******, *******************, not graph.facebook.com (456.5 ms)